1. Field of the Invention
The present invention relates to an inductor, and more particularly, to an inductor which has a coil wound around a ferrite core.
2. Description of Related Art
A well-known type of inductor is one which has a coil wound around a ferrite core. In order to obtain an inductor which has a low insertion loss in a high frequency band (10-1000 MHz), a ferrite core produced by low-temperature firing is generally used. However, the ferrite core produced by low-temperature firing has a small mechanical strength. For this reason, a low-temperature-sintered oxidized metal (for example, BiO.sub.2 or PbO) is added to the material of the ferrite core such that the produced ferrite core can endure loads at the time of automatic insertion and other occasions.
However, when an inductor which has a ferrite core containing a low-temperature-sintered oxidized metal is soldered to a printed circuit board, the low-temperature-sintered oxidized metal is reduced by an organic acid contained in a flux used for the soldering. Thereby, the insulation resistance of the ferrite core is lowered.